function crateToBlob () {
  // 注入blob对象
  if (!HTMLCanvasElement.prototype.toBlob) {
    Object.defineProperty(HTMLCanvasElement.prototype, 'toBlob', {
      value: function (callback, type, quality) {
        var canvas = this
        setTimeout(function () {
          var binStr = atob(canvas.toDataURL(type, quality).split(',')[1])
          var len = binStr.length
          var arr = new Uint8Array(len)
          for (var i = 0; i < len; i++) {
            arr[i] = binStr.charCodeAt(i)
          }
          callback(new Blob([arr], { type: type || 'image/png' }))
        })
      }
    })
  }
}
function IEVersion () {
  var userAgent = navigator.userAgent
  var isIE = userAgent.indexOf('compatible') > -1 && userAgent.indexOf('MSIE') > -1
  var isEdge = userAgent.indexOf('Edge') > -1 && !isIE
  var isIE11 = userAgent.indexOf('Trident') > -1 && userAgent.indexOf('rv:11.0') > -1
  if (isIE) {
    var reIE = new RegExp('MSIE (\\d+\\.\\d+);')
    reIE.test(userAgent)
    var fIEVersion = parseFloat(RegExp['$1'])
    if (fIEVersion === 7) {
      return 7
    } else if (fIEVersion === 8) {
      return 8
    } else if (fIEVersion === 9) {
      return 9
    } else if (fIEVersion === 10) {
      return 10
    } else {
      return 6
    }
  } else if (isEdge) {
    return 'edge'
  } else if (isIE11) {
    return 11
  } else {
    return -1
  }
}
export default {
  crateToBlob,
  IEVersion
}
